Flow control valve and cooling system

ABSTRACT

Provided is a flow control valve and a cooling system, with which a pressure loss can be reduced. A rotor 12 includes a first guide portion 43 on the outer circumferential side of an extending portion 42 fixed to a drive shaft 13 and protruding into a space inside the rotor 12. The first guide portion 43 has a radial outer shape which increases from an x-axis positive direction side toward an x-axis negative direction side.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 16/331,884, filed on Mar. 8, 2019, which is a 371 ofPCT/JP2017/031128, filed on Aug. 30, 2017, which is based upon andclaims priority to Japanese patent application 2016-183645, filed onSep. 21, 2016, which are hereby incorporated by reference in theirentireties.

TECHNICAL FIELD

The invention relates to flow control valves and cooling systems.

BACKGROUND ART

The flow control valves generally known are those with a rotatable valveelement (Patent Literature 1, for example).

CITATION LIST Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication (Kokai) No.2004-76647

SUMMARY OF INVENTION Technical Problem

The flow control valves in relevant art cause a large fluid pressureloss due to a valve-element supporting structure which is protrudinginside a valve element.

An object of the invention is to provide a flow control valve and acooling system, with which a pressure loss can be reduced.

Solution to Problem

According to a flow control valve of one embodiment of the invention, avalve element includes a first guide portion on an outer circumferentialside of an extending portion which is fixed to a drive shaft andprotruding into a space inside the valve element. The first guideportion has a radial outer shape which increases from one axial sidetoward the other axial side.

The one embodiment of the invention thus can reduce the pressure loss.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of a cooling system 1 according to anEmbodiment 1.

FIG. 2 is a perspective view of an MCV 9 according to the Embodiment 1.

FIG. 3 is an exploded perspective view of the MCV 9 according to theEmbodiment 1.

FIG. 4 is a plan view of the MCV 9 according to the Embodiment 1.

FIG. 5 is a perspective view of a section taken along line S5-S5 of FIG.4 as viewed from the direction indicated by the arrow.

FIG. 6 is a sectional view taken along line S5-S5 of FIG. 4 as viewedfrom the direction indicated by the arrow.

FIG. 7 is a sectional view taken along line S7-S7 of FIG. 4 as viewedfrom the direction indicated by the arrow.

FIG. 8 is a perspective view (showing a housing only) of a section takenalong a line S8-S8 of FIG. 4 as viewed from the direction indicated bythe arrow.

FIG. 9 is a perspective view of a rotor 12 according to the Embodiment1.

FIG. 10 is a perspective view of the rotor 12 of FIG. 9 in a positionturned at 180 degrees.

FIG. 11 is a sectional view taken along line S5-S5 of FIG. 4 accordingto an Embodiment 2 as viewed from the direction indicated by the arrow.

FIG. 12 is a sectional view taken along line S5-S5 of FIG. 4 accordingto an Embodiment 3 as viewed from the direction indicated by the arrow.

FIG. 13 is a schematic view of a cooling system 100 according to anEmbodiment 4.

DESCRIPTION OF EMBODIMENTS Embodiment 1

FIG. 1 is a schematic view of a cooling system 1 according to anEmbodiment 1.

The cooling system 1 of the Embodiment 1 includes a circuit 7 configuredto pass coolant (fluid), which has cooled an engine 2 functioning as aheat source, through a plurality of heat exchangers (radiator 3,transmission fluid warmer 4, heater 5) and then deliver the coolant backto the engine 2 via a water pump 6. The engine 2 is, for example, agasoline engine installed in a vehicle. The radiator 3 cools the coolantthrough heat exchange between the coolant and relative wind. Thetransmission fluid warmer 4 cools the coolant through heat exchangebetween the coolant and a transmission fluid. The transmission fluidwarmer 4 raises the temperature of the transmission fluid when theengine 2 is cold, and also functions as a fluid cooler for cooling thetransmission fluid after the warm-up of the engine 2 is finished. Theheater 5 cools the coolant through heat exchange between the coolant andthe air blown into a vehicle interior while the vehicle interior isbeing heated. The water pump 6 is rotationally driven by a driving forceof the engine 2 and feeds the engine 2 with the coolant from theradiator 3, the transmission fluid warmer 4, and the heater 5. Thecircuit 7 includes a normally-open water passage 7 a for constantlycirculating the coolant, bypassing the heat exchangers 3, 4 and 5. Awater temperature sensor 8 for detecting coolant temperature (watertemperature) is placed in the normally-open water passage 7 a. Amechanical control valve (hereinafter, referred to as MCV) 9 is a flowrate control valve configured to adjust a flow rate of the coolant whichis fed from the engine 2 to the heat exchangers 3, 4 and 5. The MCV 9will be discussed later in details. An engine control unit 101 isconfigured to control a valve rotation angle of the MCV 9 in accordancewith the water temperature detected by the water temperature sensor 8,information (engine negative pressure, throttle opening degree, etc.) ofthe engine 2, and the like.

A configuration of the MCV 9 will be now explained.

FIG. 2 is a perspective view of the MCV 9 according to the Embodiment 1.FIG. 3 is an exploded perspective view of the MCV 9. FIG. 4 is a planview of the MCV 9. FIG. 5 is a perspective view of a section taken alongline S5-S5 of FIG. 4 as viewed from the direction indicated by thearrow. FIG. 6 is a sectional view taken along line S5-S5 of FIG. 4 asviewed from the direction indicated by the arrow. FIG. 7 is a sectionalview taken along line S7-S7 of FIG. 4 as viewed from the directionindicated by the arrow. FIG. 8 is a perspective view (showing a housingonly) of a section taken along a line S8-S8 of FIG. 4 as viewed from thedirection indicated by the arrow. FIG. 9 is a perspective view of arotor 12 according to the Embodiment 1. FIG. 10 is a perspective view ofthe rotor 12 of FIG. 9 in a position turned at 180 degrees.

The MCV 9 includes the housing 10, a drive mechanism 11, the rotor(valve element) 12, and a drive shaft 13. Hereinafter, an x-axisrepresents a direction along a rotational axis of the drive shaft 13. Adirection from the drive mechanism 11 toward the rotor 12 along thex-axis is referred to as an x-axis positive direction, and an oppositedirection as an x-axis negative direction. A radiation direction of thex-axis is referred to as a radial direction, and a direction around thex-axis as a circumferential direction.

First, a configuration of the housing 10 will be explained.

The housing 10 is formed by casting out of an aluminum alloy material,for example. The housing 10 includes a base portion 14, acircumferential wall 15, a main communicating port 16, a plurality ofsub-communicating ports 17, and a bearing portion 18. The base portion14 has a substantially disk-like shape and is perpendicular to thex-axis direction. The drive shaft 13 extends in the x-axis directionthrough a center of the base portion 14. A stopper 14 a is provided inan x-axis positive direction-side surface of the base portion 14. Thestopper 14 a is protruding in the x-axis positive direction. Thecircumferential wall 15 has a substantially cylindrical shape andextends from an outer circumference of the base portion 14 in the x-axispositive direction. The circumferential wall 15 is tapered in such a waythat an inner diameter increases from the x-axis negative direction sidetoward the x-axis positive direction side. A valve element housingportion 19 is provided on an inner circumferential side of thecircumferential wall 15. The valve element housing portion 19 is asubstantially columnar space. The rotor 12 is accommodated in the valveelement housing portion 19. The main communicating port 16 is a circularopening portion which is formed at an x-axis positive direction end ofthe circumferential wall 15 (x-axis positive direction end of thehousing 10). The main communicating port 16 is in communication with thevalve element housing portion 19. A water passage, which extends fromthe engine 2, and the valve element housing portion 19 are connectedtogether through the main communicating port 16. The plurality ofsub-communicating ports 17 are circular opening portions formed in thecircumferential wall 15 and communicate with the valve element housingportion 19. The plurality of sub-communicating ports 17 comprise a firstsub-communicating port 17 a, a second sub-communicating port 17 b, and athird sub-communicating port 17 c. The first sub-communicating port 17 ahas the smallest opening area. The third sub-communicating port 17 c hasthe largest opening area. The second sub-communicating port 17 b islocated further on the x-axis negative direction side than the firstsub-communicating port 17 a. The third sub-communicating port 17 c islocated further on the x-axis positive direction side than the firstsub-communicating port 17 a. As viewed from the x-axis negativedirection side, the second sub-communicating port 17 b and the thirdsub-communicating port 17 c are located away from the firstsub-communicating port 17 a clockwise by 90 and 180 degrees,respectively.

Outlets (conduits) 20 a, 20 b and 20 c functioning as pipe joints arefixed to radial outer sides of the sub-communicating ports 17 a, 17 band 17 c. The first outlet 20 a connects the first sub-communicatingport 17 a and a water passage extending toward the heater 5. The secondoutlet 20 b connects the second sub-communicating port 17 b and a waterpassage extending toward the transmission fluid warmer 4. The thirdoutlet 20 c connects the third sub-communicating port 17 c and a waterpassage extending toward the radiator 3. Outer circumferences of thefirst and second outlets 20 a and 20 b and respective innercircumferences of the first and second sub-communicating ports 17 a and17 b are sealed with O-rings 21 a and 21 b at radial inner ends of thefirst and second outlets 20 a and 20 b. A fourth sub-communicating port17 d is formed in the housing 10. The fourth sub-communicating port 17 dis in constant communication with the main communicating port 16,regardless of a rotation angle of the rotor 12. A fourth outlet 20 dfunctioning as a pipe joint is fixed to a radial outer side of thefourth sub-communicating port 17 d. The fourth outlet 20 d connects thefourth sub-communicating port 17 d and the normally-open water passage 7a. A fifth sub-communicating port 17 e is also formed in the housing 10.The fifth sub-communicating port 17 e is in communication with thefourth sub-communicating port 17 d. A water passage, not shown, isformed in the third outlet 20 c. This water passage connects the fifthsub-communicating port 17 e and the first sub-communicating port 17 a. Athermostat 22 is accommodated in this water passage. The thermostat 22has a fail-safe function which opens the water passage when the watertemperature is excessively increased (to 100 or higher degrees Celsius,for example), and thus accelerates the reduction of the watertemperature. The x-axis positive direction end of the housing 10 hasthree attaching holes 23 into which bolls are inserted when the MCV 9 isbolted to the engine 2.

The bearing portion 18 supports the drive shaft 13 in such a way thatthe drive shaft 13 is rotatable relative to the housing 10. The bearingportion 18 is formed into a substantially cylindrical shape extendingalong the x-axis direction. The bearing portion 18 has an x-axisnegative direction end which is protruding further toward the x-axisnegative direction side than an x-axis negative direction end of thebase portion 14. The bearing portion 18 further has an x-axis positivedirection end which is protruding further toward the x-axis positivedirection side than an x positive direction end of the base portion 14.The x-axis positive direction end of the bearing portion 18 is locatedfurther on the x-axis negative direction side than the x-axis positivedirection end of the second sub-communicating port 17 b. A through-hole18 a is formed in a center of the bearing portion 18. The drive shaft 13extends through the through-hole 18 a. Inside the through-hole 18 a, thebearing portion 18 includes a radial thrust bearing (first radialbearing) 24, a dust seal 25, a liquid-tight seal 26, and a thrustbearing 27. The radial thrust bearing 24 is located at the x-axisnegative direction end of the bearing portion 18 and receives radial andx-axis forces from the drive shaft 13. The dust seal 25 is locatedbetween the radial thrust bearing 24 and the liquid-tight seal 26 in thex-axis direction and prevents the coolant, which has flown into thebearing portion 18, from entering the drive mechanism 11. Theliquid-tight seal 26 is located between the dust seal 25 and the thrustbearing 27 in the x-axis direction and prevents the coolant from flowingout of the valve element housing portion 19. The thrust bearing 27 islocated at the x-axis positive direction end of the bearing portion 18and receives the x-axis force from the drive shaft 13. The housing 10has a relief hole 28 connecting the through-hole 18 a and a space on anx-axis negative direction side of the base portion 14. The relief hole28 is located on the x-axis negative direction side of the stopper 14 a.The relief hole 28 functions to discharge the coolant and air, whichhave flown into the bearing portion 18 (through-hole 18 a), to theoutside of the housing 10. The relief hole 28 is inclined with respectto the x-axis. The relief hole 28 extends from the through-hole 18 a inthe x-axis negative direction and a radially outward direction to openin the x-axis negative direction side of the base portion 14. The reliefhole 28 extends from the through-hole 18 a in the x-axis negativedirection and a radially outward direction to open in the x-axisnegative direction side of the base portion 14.

A configuration of the drive mechanism 11 will be explained below.

The drive mechanism 11 is located on the x-axis negative direction sideof the base portion 14 and rotationally drives the drive shaft 13. Thedrive mechanism 11 includes an electric motor 29, a motor worm 30, anintermediate gear 31, an intermediate worm 32, and a rotor gear 33. Theelectric motor 29 is controlled by the engine control unit 101. Theelectric motor 29 is accommodated in the housing 10 with an output shaft29 a oriented in the x-axis negative direction. The motor worm 30rotates integrally with the output shaft 29 a. The intermediate gear 31is meshingly engaged with the motor worm 30. The intermediate worm 32 isformed integrally with the intermediate gear 31. An intermediate shaft34 extends through the center of the intermediate gear 31 and theintermediate worm 32. The intermediate shaft 34 has an axisperpendicular to the x-axis. The intermediate shaft 34 is supported bytwo shaft support portions 35 a and 35 b so as to be rotatable about theaxis of the intermediate shaft 34. The shaft support portions 35 a and35 b extend from the base portion 14 in the x-axis negative direction.The rotor gear 33 is fixed to an x-axis negative direction end of thedrive shaft 13 and rotates integrally with the drive shaft 13. A magnet36 is attached to the x-axis negative direction end of the drive shaft13. The magnet 36 is not shown in the attached drawings except FIG. 3.The motor worm 30, the intermediate gear 31, the intermediate worm 32,and the rotor gear 33 are accommodated in a gear housing 37. The gearhousing 37 includes a magnetoresistive (MR) sensor, not shown. The MRsensor detects a rotation angle of the drive shaft 13, namely, arotation angle of the rotor 12, on the basis of a change caused in amagnetic field by the rotation of the drive shaft 13. The rotation angledetected by the MR sensor is transmitted to the engine control unit 101.

A configuration of the rotor 12 will be now explained.

The rotor 12 is accommodated in the valve element housing portion 19.The rotor 12 is made of, for example, a synthetic resin material. Therotor 12 includes a bottom portion 38, an outer circumferential portion39, a main opening portion 40, a plurality of sub-opening portions 41,and an extending portion 42. The bottom portion 38 is located on thex-axis negative direction side of the rotor 12 and perpendicular to thex-axis direction. The bottom portion 38 has a donut-like shape, a littleover 180-degree-angle segment of which is cut away with only an outercircumferential portion of the segment left, as viewed from the x-axisnegative direction side. The outer circumferential portion 39 has asubstantially cylindrical shape extending from an outer circumference ofthe bottom portion 38 in the x-axis positive direction. The outercircumferential portion 39 is tapered in such a way that an innerdiameter increases from the x-axis negative direction side toward thex-axis positive direction side. The outer circumferential portion 39includes a flange portion 39 a extending from the x-axis positivedirection end of the outer circumferential portion 39 in the radiallyoutward direction. A slide bearing (second radial bearing) 44 isprovided near the x-axis positive direction end of the circumferentialwall 15 and further on the x-axis negative direction side than theflange portion 39 a. The slide bearing 44 supports the rotor 12 in sucha way that the rotor 12 is rotatable relative to the housing 10. Theslide bearing 44 receives the radial force from the rotor 12. The mainopening portion 40 is a circular opening portion which is formed at thex-axis positive direction end of the outer circumferential portion 39(x-axis positive direction end of the rotor 12). The main openingportion 40 is in communication with the main communicating port 16. Theplurality of sub-opening portions 41 are opening portions formed in theouter circumferential portion 39. The plurality of sub-opening portions41 comes into communication with the respective plurality ofsub-communicating ports 17 a, 17 b and 17 c when the rotor 12 ispositioned within a predetermined rotation angle range. The plurality ofopening portions 41 comprise a first sub-opening portion 41 a, a secondsub-opening portion 41 b, and a third sub-opening portion 41 c. Thefirst sub-opening portion 41 a corresponds to the firstsub-communicating port 17 a. The second sub-opening portion 41 bcorresponds to the second sub-communicating port 17 b. The thirdsub-opening portion 41 c corresponds to the third sub-communicating port17 c. The second sub-opening portion 41 b is located further on thex-axis negative direction side than the first sub-opening portion 41 a.The third sub-opening portion 41 c is located further on the x-axispositive direction side than the first sub-opening portion 41 a. Thesecond sub-opening portion 41 b is formed into an elongate holeextending in a circumferential direction. The first and thirdsub-opening portions 41 a and 41 c each have a circular shape. Thesecond sub-opening portion 41 b is shorter in x-axis length than thefirst sub-opening portion 41 a. The third sub-opening portion 41 c islarger in opening area than the second sub-opening portion 41 b. Thefirst sub-opening portion 41 a includes two opening portions 41 a 1 and41 a 2. The opening portion 41 a 1 is for summer use, whereas theopening portion 41 a 2 is for winter use. The third sub-opening portion41 c also includes two opening portions 41 c 1 and 41 c 2. The openingportion 41 c 1 is for summer use, whereas the opening portion 41 c 2 isfor winter use. The first sub-opening portion 41 a (41 a 1, 41 a 2)overlaps with a first guide portion 43 in the x-axis direction.

The extending portion 42 extends from the outer circumference of thebottom portion 38 in the x-axis positive direction to be joined to thex-axis positive direction end of the drive shaft 13. The extendingportion 42 includes a tip portion 42 a, a cylindrical portion (tubularportion) 42 b, and a second guide portion 42 c. The tip portion 42 a isprovided at an x-axis positive direction end of the extending portion42. The tip portion 42 a is located on the x-axis positive directionside of the bearing portion 18 of the housing 10 and fixed to the driveshaft 13. A metallic insert 42 d for reinforcement is embedded in acenter of the tip portion 42 a and in a joined portion between the tipportion 42 a and the drive shaft 13. The rotor 12 is insert-molded withthe insert 42 d used as an insert. An x-axis positive direction side ofthe tip portion 42 a overlaps with the first sub-communicating port 17 aof the housing 10 in the x-axis direction. An x-axis positive directionend of the tip portion 42 a is located further on the x-axis negativedirection side than the x-axis positive direction end of the firstsub-communicating port 17 a, and yet further on the x-axis positivedirection side than the x-axis negative direction side of the firstsub-communicating port 17 a. The tip portion 42 a has an outercircumferential surface which is provided with the first guide portion43. The first guide portion 43 is tapered in such a way that a radialdimension increases from the x-axis positive direction side toward thex-axis negative direction side. The cylindrical portion 42 b is formedinto a cylindrical shape which extends from the first guide portion 43in the x-axis negative direction. The cylindrical portion 42 b has aninner diameter which is larger than an outer diameter of the bearingportion 18. The cylindrical portion 42 b overlaps with the bearingportion 18 in the x-axis direction. An x-axial end of the cylindricalportion 42 b is connected to the second guide portion 42 c in an areawhere the cut-away segment of the bottom portion 38 is located in thecircumferential direction and connected to the bottom portion 38 in anarea where the other segment is located. The second guide portion 42 cis provided in the cut-away segment of the bottom portion 38 in thecircumferential direction and thus connects the cylindrical portion 42 band the outer circumference of the bottom portion 38. The second guideportion 42 c is connected to an opening rim on an x-axis negativedirection side of the second sub-opening portion 41 b. The second guideportion 42 c is tapered in such a way that a radial outer shapeincreases from the x-axis positive direction side toward the x-axisnegative direction side. The bottom portion 38 includes two connectingportions 38 a and 38 b which are connected to the second guide portion42 c. The connecting portions 38 a and 38 b extend along the x-axisdirection. Each of the connecting portions 38 a and 38 b iscircumferentially engaged with the stopper 14 a of the base portion 14when the rotor 12 is positioned at the corresponding predeterminedrotation angle. The rotor 12 rotates clockwise as viewed from the x-axisnegative direction side from a position where the connecting portion 38a is in contact with the stopper 14 a of the base portion 14. The rotor12 is rotatable within a range of an angle of a little less than 180degrees upon till the connecting portion 38 b comes into contact withthe stopper 14 a.

Seal portions 45, 46 and 47 provided to the sub-communicating ports 17a, 17 b and 17 c will be explained below.

The first seal portion 45 is provided to the first sub-communicatingport 17 a. The first seal portion 45 prevents the coolant from leakingfrom the first sub-communicating port 17 a into a radial clearancebetween the circumferential wall 15 and the outer circumferentialportion 39 while the first sub-communicating port 17 a and the firstsub-opening portion 41 a are in communication. The first seal portion 45includes a rotor seal 45 a, an O-ring 45 b, and a coil spring 45 c. Therotor seal 45 a has a cylindrical shape and is inserted in the firstsub-communicating port 17 a. The rotor seal 45 a has a radial inner endwhich is in contact with the outer circumferential portion 39. TheO-ring 45 b seals a gap between an inner circumferential surface of thefirst sub-communicating port 17 a and an outer circumferential surfaceof the rotor seal 45 a. The coil spring 45 c is radially interposedbetween the rotor seal 45 a and the first outlet 20 a in a compressedposition to bias the rotor seal 45 a in a radially inward direction. Thesecond seal portion 46 is provided to the second sub-communicating port17 b. The second seal portion 46 prevents the coolant from leaking fromthe second sub-communicating port 17 b into the radial clearance betweenthe circumferential wall 15 and the outer circumferential portion 39while the second sub-communicating port 17 b and the second sub-openingportion 41 b are in communication. The second seal portion 46 includes arotor seal 46 a, an O-ring 46 b, and a coil spring 46 c. The rotor seal46 a has a cylindrical shape and is inserted in the secondsub-communicating port 17 b. The rotor seal 46 a has a radial inner endwhich is in contact with the outer circumferential portion 39. TheO-ring 46 b seals a gap between an inner circumferential surface of thesecond sub-communicating port 17 b and an outer circumferential surfaceof the rotor seal 46 a. The coil spring 46 c is radially interposedbetween the rotor seal 46 a and the second outlet 20 b in a compressedposition to bias the rotor seal 46 a in the radially inward direction.The third seal portion 47 is provided to the third sub-communicatingport 17 c. The third seal portion 47 prevents the coolant from leakingfrom the third sub-communicating port 17 c into the radial clearancebetween the circumferential wall 15 and the outer circumferentialportion 39 while the third sub-communicating port 17 c and the thirdsub-opening portion 41 c are in communication. The third seal portion 47includes a rotor seal 47 a, an O-ring 47 b, and a coil spring 47 c. Therotor seal 47 a has a cylindrical shape and is inserted in the thirdsub-communicating port 17 c. The rotor seal 47 a has a radial inner endwhich is in contact with the outer circumferential portion 39. TheO-ring 47 b seals a gap between an inner circumferential surface of thethird sub-communicating port 17 c and an outer circumferential surfaceof the rotor seal 47 a. The coil spring 47 c is radially interposedbetween the rotor seal 47 a and the third outlet 20 c in a compressedposition to bias the rotor seal 47 a in the radially inward direction.

The following description will explain the operation and advantageouseffects of the MCV 9 of the Embodiment 1.

The MCV 9 of the Embodiment 1 is so configured that the extendingportion 42 is protruding into the space inside the rotor 12. The coolantflowing from the main opening portion 40 toward the x-axis negativedirection side therefore collides with the extending portion 42. Thiscauses stagnation of the coolant and might incur a pressure loss of thecoolant. If the first sub-opening portion 41 a and the secondsub-opening portion 41 b are provided further on the x-axis positivedirection side than the extending portion 42, the pressure loss of thecoolant can be reduced. On the other hand, this increases an x-axisdimension of the rotor 12, resulting in an increase in size of the MCV9.

For a solution to the above issue, the rotor 12 of the Embodiment 1includes the first guide portion 43 on the outer circumferential side ofthe extending portion 42, which has the radial outer shape whichincreases from the x-axis positive direction side toward the x-axisnegative direction side. This causes the coolant to flow in the radiallyoutward direction along the shape of the first guide portion 43,allowing the coolant to smoothly flow from the main opening portion 40to the first sub-opening portion 41 a and the second sub-opening portion41 b. Furthermore, the coolant is prevented from colliding with theextending portion 42, which further prevents the stagnation of thecoolant in the vicinity of the extending portion 42. This reduces thepressure loss of the MCV 9. There is no need to increase the x-axisdimension of the rotor 12, which prevents the increase in size of theMCV 9.

The extending portion 42 includes the cylindrical portion 42 b extendingfrom the first guide portion 43 toward the x-axis negative directionside. This allows a portion of the bearing portion 18 to be accommodatedin the cylindrical portion 42 b and thus makes the bearing portion 18overlap with the cylindrical portion 42 b in the x-axis direction. TheMCV 9 can be accordingly shortened in x-axis dimension.

The extending portion 42 includes the second guide portion 42 c whichconnects the cylindrical portion 42 b and the outer circumference of thebottom portion 38. The second guide portion 42 c has a radial outerdiameter which increases from the x-axis positive direction side towardthe x-axis negative direction side. The second guide portion 42 c isconnected to the opening rim on the x-axis negative direction side ofthe second sub-opening portion 41 b. This causes the coolant to flowfrom the main opening portion 40 toward the second sub-opening portion41 b along the shape of the second guide portion 42 c, allowing thecoolant to more smoothly flow from the main opening portion 40 to thesecond sub-opening portion 41 b. The pressure loss therefore can befurther reduced.

The rotor 12 includes the connecting portions 38 a and 38 b which extendin the x-axis direction and connect the bottom portion 38 and the secondguide portion 42 c. This makes it possible to regulate the rotationangle range of the rotor 12 to fall into the predetermined rotationangle range by using the stopper 14 a which is located on the housing 10side.

The first sub-opening portion 41 a overlaps with the first guide portion43 in the x-axis direction. This allows the coolant to more smoothlyflow from the main opening portion 40 to the first sub-opening portion41 a. The pressure loss therefore can be further reduced.

The MCV 9 includes the seal portions 45, 46 and 47 which prevent thecoolant from leaking from the sub-opening portions 41 a, 41 b and 41 cinto the radial clearance between the housing 10 and the outercircumferential portion 39. This prevents an internal leak of the MCV 9and restrains a decrease in flow rate of the coolant.

The third sub-opening portion 41 c is provided further on the x-axispositive direction side than the first sub-opening portion 41 a and islarger in opening area than the first and second sub-opening portions 41a and 41 b. Being the closest to the main opening portion 40 and thelargest in opening area among the sub-opening portions 41 a, 41 b and 41c, the third sub-opening portion 41 a allows the largest amount ofcoolant to pass therethrough among the sub-opening portions 41 a, 41 band 41 c. The third sub-communicating port 17 c of the third sub-openingportion 41 a is therefore suitable for connection to the radiator 3which requires the largest amount of coolant among the heat exchangers3, 4 and 5 installed in the vehicle.

The first sub-opening portion 41 a includes the summer-use openingportion 41 a 1 and the winter-use opening portion 41 a 2. This makes itpossible to achieve the control on flow rate of the coolant inaccordance with ambient temperature. The third sub-opening portion 41 calso provides similar advantageous effects.

The bearing portion 18 includes the radial thrust bearing 24 whichrotatably supports the drive shaft 13. The circumferential wall 15includes the slide bearing 44 which is provided at the x-axis positivedirection end of the circumferential wall 15 and rotatably supports thex-axis positive direction end of the outer circumferential portion 39.In other words, the rotor 12 is provided, at both x-axial ends thereof,with radial bearings which receive a force coming from the radial(radiation) direction. This makes it possible to stably support therotor 12 and facilitate the rotation of the rotor 12.

The housing 10 includes the relief hole 28 which extends from thebearing portion 18 in a vehicle upward direction (x-axis negativedirection) to be connected to the housing 10. The relief hole 28 isinclined with respect to the x-axis. This enables the air which hasentered the bearing portion 18 to be discharged out of the housing 10.The inclination of the relief hole 28 with respect to the x-axiseliminates the necessity of increasing the x-axis dimension of thehousing 10.

The bearing portion 18 includes the thrust bearing 27 which supports thedrive shaft 13. The rotor 12 receives the force on the x-axis negativedirection side thereof from the coolant introduced to the main openingportion 40. The rotor 12 is supported by the thrust bearing 27, whichmakes it possible to support an x-axis (thrust) force acting on therotor 12.

The outer circumferential portion 39 is tapered in such a way that theinner diameter increases from the x-axis negative direction side towardthe x-axis positive direction side. This makes it easy to remove theinsert-molded rotor 12 from a resin mold, facilitating a manufacturingprocess of the rotor 12.

The outer circumferential portion 39 includes a flange portion 39 a atthe x-axis positive direction end thereof. This prevents the coolantfrom leaking into the radial clearance between the inner circumferentialsurface of the circumferential wall 15 and the outer circumferentialsurface of the outer circumferential portion 39 at the x-axis positivedirection end of the outer circumferential portion 39. This prevents theinternal leak of the MCV 9 and restrains a decrease in flow rate of thecoolant.

The cooling system 1 of the Embodiment 1 includes the plurality of heatexchangers 3, 4 and 5, the circuit 7 which cools the engine 2 bycirculating the coolant which has passed through the heat exchanges 3, 4and 5 to be cooled down by the heat exchanges 3, 4 and 5, and the MCV 9which controls the flow rate of the coolant circulating in the circuit7. It is then possible to downsize the cooling system 1 and reduce thepressure loss.

The MCV 9 controls the flow rate of the coolant which flows from theengine 2 toward the heat exchangers 3, 4 and 5. The main communicatingport 16 is connected to the engine 2 side. The sub-communicating ports17 a, 17 b and 17 c are connected to the heat exchangers 3, 4 and 5. Itis therefore possible to restrain the pressure loss of the coolant whichflows from the engine 2 toward the heat exchangers 3, 4 and 5.

Embodiment 2

FIG. 11 is a sectional view taken along line S5-S5 of FIG. 4 accordingto an Embodiment 2 as viewed from the direction indicated by the arrow.

An MCV 90 of the Embodiment 2 differs from the MCV 9 of the Embodiment 1in the shape of a second guide portion 42 c. The Embodiment 2 includes asingle first sub-opening portion 41 a and a single third sub-openingportion 41 c. According to the Embodiment 2, a bearing portion 18 and acylindrical portion 42 b do not overlap with each other in the x-axisdirection. The second guide portion 42 c of the Embodiment 2 includesnot only a second guide portion 42 c 2 corresponding to a secondsub-opening portion, which is connected to an opening rim on an x-axisnegative direction side of a second sub-opening portion 41 b shown inFIG. 7, but also a second guide portion 42 c 1 corresponding to a firstsub-opening portion, which is connected to an opening rim on an x-axisnegative direction side of the first sub-opening portion 41 a, and asecond guide portion 42 c 3 corresponding to a third sub-openingportion, which is connected to an opening rim on an x-axis negativedirection side of the third sub-opening portion 41 c. The second guideportion 42 c 1 corresponding to the first sub-opening portion connectsthe cylindrical portion 42 b and an outer circumferential portion 39.The second guide portion 42 c 1 corresponding to the first sub-openingportion is tapered in such a way that a radial outer diameter increasesfrom an x-axis positive direction side toward an x-axis negativedirection side. The second guide portion 42 c 3 corresponding to thethird sub-opening portion connects a tip portion 42 a and the outercircumferential portion 39. The second guide portion 42 c 3corresponding to the third sub-opening portion is tapered in such a waythat a radial outer diameter increases from an x-axis positive directionside toward an x-axis negative direction side. The Embodiment 2 isotherwise similar in configuration to the Embodiment 1, and furtherdescriptions of the configuration of the Embodiment 2 will be omitted.

The MCV 90 of the Embodiment 2 includes the second guide portion 42 c 1corresponding to the first sub-opening portion, which is connected tothe opening rim on the x-axis negative direction side of the firstsub-opening portion 41 a. This causes the coolant to flow from a mainopening portion 40 toward the first sub-opening portion 41 a along ashape of the second guide portion 42 c 1 corresponding to the firstsub-opening portion, allowing the coolant to more smoothly flow from themain opening portion 40 to the first sub-opening portion 41 a. Thepressure loss therefore can be further reduced. The second guide portion42 c 3 corresponding to the third sub-opening portion also providessimilar advantageous effects.

Embodiment 3

FIG. 12 is a sectional view taken along line S5-S5 of FIG. 4 accordingto an Embodiment 3 as viewed from the direction indicated by the arrow.

An MCV 91 of the Embodiment 3 differs from the MCV 90 of the Embodiment2 in shapes of outlets 20 a, 20 b and 20 c connected tosub-communicating ports 17 a, 17 b and 17 c. End portions of the outlets20 a, 20 b and 20 c, which are located on the sub-communicating ports 17a, 17 b and 17 c side (radially inward side), each have an innerdiameter which is tapered in such a way that opening area graduallyincreases from a radially inward side toward a radially outward side.Each of the sub-communicating ports 17 a, 17 b and 17 c is also taperedin such a way that opening area gradually increases from the radiallyinward side toward the radially outward side. The Embodiment 3 isotherwise similar in configuration to the Embodiment 2, and furtherdescriptions of the configuration of the Embodiment 3 will be omitted.

The MCV 91 of the Embodiment 3 makes it possible to reduce the pressureloss of the coolant since the sub-communicating ports 17 a, 17 b and 17c are connected to the outlets 20 a, 20 b and 20 c whose opening areaincreases from the radially inward side toward the radially outwardside.

Embodiment 4

FIG. 13 is a schematic view of a cooling system 100 according to anEmbodiment 4.

In the cooling system 100 of the Embodiment 4, an MCV 9 adjusts a flowrate of coolant which is fed from heat exchangers 3, 4 and 5 to a waterpump 6. The MCV 9 includes a main communicating port 16 which connects avalve element housing portion 19 and a water passage extending towardthe water pump 6. A first outlet 20 a connects a water passage, whichextends from the heater 5, and a first sub-communicating port 17 a. Asecond outlet 20 b connects a water passage, which extends from thetransmission fluid warmer 4, and a second sub-communicating port 17 b. Athird outlet 20 c connects a water passage, which extends from theradiator 3, and a third sub-communicating port 17 c. The Embodiment 4 isotherwise similar in configuration to the Embodiment 1, and furtherdescriptions of the configuration of the Embodiment 4 will be omitted.

The cooling system 100 of the Embodiment 4 is so configured that the MCV9 controls the flow rate of the coolant which flows from the heatexchangers 3, 4 and 5 toward an engine 2 (intake side of the water pump6), that a main communicating port 16 is connected to the engine 2, andthat the sub-communicating ports 17 a, 17 b and 17 c are connected tothe heat exchangers 3, 4 and 5. It is then possible to restrain apressure loss of the coolant which flows from the heat exchangers 3, 4and 5 toward the engine 2.

Other Embodiments

The embodiments for carrying out the invention have been explained. Thespecific configuration of the invention is not limited to those of theembodiments, and all design modifications and the like made withoutdeviating from the gist of the invention are intended to be included inthe invention.

The heat source of the cooling system does not have to be an engine andmay be an internal combustion engine, a fuel cell or other like heatsources.

The radial thrust bearing of the bearing portion may be a radialbearing.

The number of the sub-communicating ports and of the sub-openingportions may be two, four or more.

Technical ideas which can be understood from the foregoing embodimentsare as follows.

According to one aspect, a flow control valve comprises a drive shaft; ahousing including a base portion through which the drive shaft extends,a circumferential wall extending from an outer circumference of the baseportion toward one axial side of an axial direction, when a directionalong an axis of the drive shaft is defined as the axial direction, avalve element housing portion being provided on an inner circumferentialside, a main communicating port provided in an end portion on the oneaxial side of the circumferential wall and communicating with the valveelement housing portion, a plurality of sub-communicating ports formedin the circumferential wall and communicating with the valve elementhousing portion, and a bearing portion formed to protrude from the baseportion toward the one axial side and configured to rotatably supportthe drive shaft; a drive mechanism provided in the other axial side ofthe base portion and configured to rotationally drive the drive shaft;and a valve element accommodated in the valve element housing portion,the valve element including a bottom portion, an outer circumferentialportion which extends from an outer circumference of the bottom portiontoward the one axial side, a main opening portion provided in an endportion on the one axial side of the outer circumferential portion andcommunicating with the main communicating port, a plurality ofsub-opening portions formed in the outer circumferential portion andcommunicating with the respective sub-communicating ports when the valveelement is positioned within a predetermined rotation angle range, anextending portion which extends from the bottom portion or the outercircumferential portion toward the one axial side and is fixed to an endportion on the one side of the drive shaft, and a first guide portionprovided on an outer circumferential side of the extending portion andhaving a radial outer shape which increase from the one axial sidetoward the other axial side, when a direction radial to the axis isdefined as a radial direction.

A further preferable aspect according to the above-described aspect isso configured that the extending portion includes a tubular portionwhich extends from the first guide portion toward the other axial side.

Another preferable aspect according to any one of the above-describedaspects is so configured that the extending portion includes a secondguide portion which connects the cylindrical portion and the outercircumference of the bottom portion or the outer circumferentialportion, the second guide portion having a radial outer shape whichincreases from the one axial side toward the other axial side.

Still another preferable aspect according to any one of theabove-described aspects is so configured that the valve element includesa connecting portion extending in the axis direction and connecting thebottom portion and the second guide portion.

Still another preferable aspect according to any one of theabove-described aspects is so configured that at least one of theplurality of sub-opening portions overlaps with the first guide portionin the axis direction.

Still another preferable aspect according to any one of theabove-described aspects includes a seal portion configured to preventfluid from leaking from one of a pair of one of the plurality ofsub-communicating ports and a corresponding one of the plurality ofsub-opening portions into a radial clearance between the housing and theouter circumferential portion.

Still another preferable aspect according to any one of theabove-described aspects is so configured that the plurality ofsub-communicating ports include a first sub-communicating port and asecond sub-communicating port provided further on the other axial sidethan the first sub-communicating port, and that the plurality ofsub-opening portions include a first sub-opening portion correspondingto the first sub-communicating port and overlapping with the first guideportion in the axis direction, and a second sub-opening portioncorresponding to the second sub-communicating port.

Still another preferable aspect according to any one of theabove-described aspects is so configured that the valve element includesa second guide portion connected to an opening rim on the other axialside of the second sub-opening portion, the second guide portion havinga radial outer shape which increases from the one axial side toward theother axial side.

Still another preferable aspect according to any one of theabove-described aspects is so configured that the plurality ofsub-communicating ports include a third sub-communicating port providedfurther on the one axial side than the first sub-communicating port, andthat the plurality of sub-opening portions include a third sub-openingportion corresponding to the third sub-communicating port and beinglarger in opening area than the first sub-opening portion.

Still another preferable aspect according to any one of theabove-described aspects is so configured that at least either the firstsub-communicating port or the second sub-communicating port comprisestwo or more first or second sub-communicating ports.

Still another preferable aspect according to any one of theabove-described aspects is so configured that the bearing portionincludes a first radial bearing which rotatably supports the driveshaft, and that the circumferential wall includes a second radialbearing which is provided in an end portion on the one axial side androtatably supports the end portion on the one axial side of the outercircumferential portion.

Still another preferable aspect according to any one of theabove-described aspects is so configured that the housing includes arelief hole which connects a bearing portion and an exterior portion ofthe housing and is inclined with respect to the axis.

Still another preferable aspect according to any one of theabove-described aspects is so configured that the bearing portionincludes a thrust bearing which supports the drive shaft.

Still another preferable aspect according to any one of theabove-described aspects is so configured that at least one of theplurality of sub-communicating ports is connected to a conduit and theopening area of the conduct increases from a radially inward side towarda radially outward side.

Still another preferable aspect according to any one of theabove-described aspects is so configured that the outer circumferentialportion has an inner diameter which increases from the other axial sidetoward the one axial side.

Still another preferable aspect according to any one of theabove-described aspects is so configured that the outer circumferentialportion includes a flange portion in an end portion on the one axialside.

From another perspective, a flow control valve comprises a drive shaft;a housing including a valve element housing portion provided in oneaxial side of an axial direction of the drive shaft, when a directionalong an axis of the drive shaft is defined as the axial direction, amain communicating port provided in the one axial side of the valveelement housing portion and communicating with the valve element housingportion, and a plurality of sub-communicating ports communicating withthe valve element housing portion from a radial direction, when adirection radial to the axis is defined as the radial direction; a drivemechanism provided in the other axial side of the drive shaft andconfigured to rotationally drive the drive shaft; and a valve elementaccommodated in the valve element housing portion, the valve elementincluding a bottom portion, an outer circumferential portion extendingfrom an outer circumference of the bottom portion toward the one axialside, a shaft support portion provided further on the one axial sidethan the bottom portion and configured to receive torque of the driveshaft, a main opening portion provided in an end portion on the oneaxial side of the outer circumferential portion and communicating withthe main communicating port, a plurality of sub-opening portions formedin the outer circumferential portion and overlapping in a radialdirection with the respective plurality of sub-communicating ports whenthe valve element is positioned within a predetermined rotation anglerange, when a direction radial to the axis is defined as the radialdirection; and a guide portion extending from an outer circumference ofthe bottom portion or the outer circumferential portion toward the oneaxial side and toward the radially inward side to be connected to theshaft support portion.

From still another perspective, a cooling system comprises a pluralityof heat exchangers configured to cool fluid which has flown into theplurality of heat exchangers; a circuit configured to cool a heat sourceby circulating the fluid which has passed through the plurality of heatexchangers to be cooled down by the heat exchangers; and a flow controlvalve configured to control a flow rate of the fluid circulated in thecircuit, the flow control valve comprising a drive shaft; a housingincluding a base portion through which the drive shaft extends, acircumferential wall extending from an outer circumference of the baseportion toward one axial side of an axial direction, when a directionalong an axis of the drive shaft is defined as the axial direction, avalve element housing portion being provided on an inner circumferentialside of the circumferential wall, a main communicating port provided inan end portion on the one axial side of the circumferential wall andcommunicating with the valve element housing portion, a plurality ofsub-communicating ports formed in the circumferential wall andcommunicating with the valve element housing portion, and a bearingportion formed to protrude from the base portion toward the one axialside and configured to rotatably support the drive shaft; a drivemechanism provided in the other axial side of the base portion andconfigured to rotationally drive the drive shaft; and a valve elementaccommodated in the valve element housing portion, the valve elementincluding a bottom portion, an outer circumferential portion extendingfrom an outer circumference of the bottom portion toward the one axialside, a main opening portion provided in an end portion on the one axialside of the outer circumferential portion and communicating with themain communicating port, a plurality of sub-opening portions formed inthe outer circumferential portion and configured to come intocommunication with the respective plurality of sub-communicating portswhen the valve element is positioned within a predetermined rotationangle range, an extending portion which extends from the bottom portionor the outer circumferential portion toward the one axial side and isfixed to an end portion on the one side of the drive shaft, and a firstguide portion provided on an outer circumferential side of the extendingportion and having a radial outer shape which increases from the oneaxial side toward the other axial side, when a direction radial to theaxis is a radial direction.

Preferably, according to the above-described aspect, the flow controlvalve controls the flow rate of the fluid which flows from the heatsource toward the plurality of heat exchangers; the main communicatingport is connected to the heat source side; and the plurality ofsub-communicating ports are connected to the plurality of heatexchangers side.

Another preferable aspect according to any one of the above-describedaspects is configured that the flow control valve controls the flow rateof the fluid which flows from the plurality of heat exchangers towardthe heat source, that the main communicating port is connected to theheat source side, and that the plurality of sub-communicating ports areconnected to the plurality of heat exchangers side.

The invention is not limited to the embodiments and includes variousmodifications. For example, the embodiments have been explained indetails for ease of understanding of the invention, and the inventiondoes not necessarily have to include all the configurations discussedabove. A part of the configuration of any one of the embodiments may bereplaced with the configuration of another embodiment. The configurationof any one of the embodiments may be incorporated into the configurationof another embodiment. It is also possible to incorporate or replace apart of the configuration of any one Of the embodiments into or with theconfiguration of another embodiment, or eliminate a part of theconfiguration of any one of the embodiments.

The present application claims priority under Japanese PatentApplication No. 2016-183645 filed on Sep. 21, 2016. The entiredisclosure of Japanese Patent Application No. 2016-183645 filed on Sep.21, 2016, including the description, claims, drawings and abstract, isincorporated herein by reference in its entirety.

REFERENCE SIGN LIST

-   1: Cooling system-   2: Engine (heat source)-   3: Radiator (heat exchanger)-   4: Transmission fluid warmer (heat exchanger)-   5: Heater (heat exchanger)-   7: Circuit-   9: Mechanical control valve (flow control valve)-   10: Housing-   11: Drive mechanism-   12: Rotor (valve element)-   13: Drive shaft-   14: Base portion-   15: Circumferential wall-   16: Main communicating port-   17: Sub-communicating port-   17 a: First sub-communicating port-   17 b: Second sub-communicating port-   17 c: Third sub-communicating port-   18: Bearing portion-   19: Valve element housing portion-   20 a: First outlet (conduit)-   20 b: Second outlet (conduit)-   20 c: Third outlet (conduit)-   24: Radial thrust hearing (first radial bearing)-   27: Thrust bearing-   28: Relief hole-   38: Bottom portion-   38 a: Connecting portion-   38 b: Connecting portion-   39: Outer circumferential portion-   39 a: Flange portion-   40: Main opening portion-   41: Sub-opening portion-   41 a: First sub-opening portion-   41 b: Second sub-opening portion-   41 c: Third sub-opening portion-   42: Extending portion-   42 b: Cylindrical portion (tubular portion)-   42 c: Second guide portion-   43: First guide portion-   44: Slide bearing (second radial bearing)-   45: First seal portion (seal portion)-   46: Second seal portion (seal portion)-   47: Third seal portion (seal portion)-   100: Cooling system

The invention claimed is:
 1. A valve apparatus comprising: a valve element including a bottom portion, a housing including a valve element housing portion configured to house therein the valve element, a first communication port that communicates between the valve element housing portion and an outside of the valve apparatus, the first communication port being open in a rotational axis direction of the valve element, and a second communication port that communicates between the valve element housing portion and an outside of the valve apparatus, the second communication port being provided on a surface of the housing that is different from a surface on which the first communication port is provided, wherein the communication condition between the first communication port and the second communication port can be changed by rotation of the valve element, and wherein the bottom portion includes an inclined portion that is inclined in the direction away from the first communication port in the rotational axis direction of the valve element toward an outer periphery side of the bottom portion from the center of the bottom portion, a restrictive portion that defines a recessed portion together with the inclined portion, the recessed portion formed so as to have a concave shape in a surface of the bottom portion on an opposite side from the first communication port, the restrictive portion extending in an axial direction of the valve element, and a stopper provided in the housing to face the bottom portion and configured to restrict a rotational range of the restrictive portion.
 2. The valve apparatus according to claim 1, wherein the recessed portion has a depth decreasing radially outward from a radial center of a rotational axis of the bottom portion.
 3. A valve apparatus comprising: a valve element formed into a shape of a bottomed cylinder extending in an axial direction and including a first end that is closed with a bottom portion and a second end that is open, the valve element including an outer peripheral portion provided with an opening portion configured to permit fluid to flow outwardly therefrom, a housing including a valve element housing portion in which the valve element is housed to be rotatable about an axis of the valve element, and a communication port that is open in the valve element housing portion and connected to an external heat exchanger, a restrictive portion that partly defines a recessed portion formed in a surface of the bottom portion on an opposite side from the communication port, the restrictive portion including surfaces extending toward the second end in the axial direction of the valve element, and a stopper provided in an end wall of the valve element housing portion which faces the bottom portion, the stopper being configured to restrict a rotational range of the restrictive portion.
 4. The valve apparatus according to claim 3, wherein the restrictive portion is a connecting portion formed between a bottom surface of the recessed portion and a surface formed closer to the first end in the axial direction than the bottom surface of the recessed portion.
 5. The valve apparatus according to claim 4, wherein the surface formed closer to the first end in the axial direction than the bottom surface of the recessed portion of the bottom portion is a planar region orthogonal to the axial direction of the valve element, and wherein the bottom surface of the recessed portion of the bottom portion is an inclined region that is inclined to an axial side of the valve element toward the second end of the valve element.
 6. The valve apparatus according to claim 5, wherein two connecting portions are formed between the planar region and the inclined region, and the stopper is formed within a rotational range of the inclined region.
 7. The valve apparatus according to claim 6, wherein the stopper is integrally formed with the end wall.
 8. A system for a vehicle comprising a fluid pump configured to pressurize and pump a fluid serving as a heat medium for refrigerating a heat source, and a valve apparatus configured to deliver fluid received from the fluid pump to a plurality of heat exchangers or a valve apparatus configured to deliver fluid received from the plurality of heat exchangers to the fluid pump, the valve apparatus including: a valve element formed into a shape of a bottomed cylinder extending in an axial direction and including a first end that is closed with a bottom portion and a second end that is open, the valve element including an outer peripheral portion provided with an opening portion configured to permit fluid to flow outwardly therefrom, a housing including a valve element housing portion in which the valve element is housed to be rotatable about an axis of the valve element, and a communication port that is open in the valve element housing portion and connected to an external heat exchanger, a restrictive portion that partly defines a recessed portion formed in surface of the bottom portion on an opposite side from the communication port, the restrictive portion including surfaces extending toward the second end in the axial direction of the valve element, and a stopper provided in an end wall of the valve element housing portion which faces the bottom portion, the stopper being configured to restrict a rotational range of the restrictive portion.
 9. The system according to claim 8, wherein the heat source is an internal combustion engine, and the heat exchangers include at least one of a radiator, a heating apparatus, or an oil cooler, and wherein the valve apparatus is configured to selectively distribute coolant water of the internal combustion engine to the at least one of the radiator, the heating apparatus, or the oil cooler. 